Any window derived from wxTopLevelWindow (such as wxDialog) shouldn't be managed by wxAUI. The reason is that wxAUI performs reparenting functions which wont work properly on top level windows. The solution is to instead implement your dialog on a wxPanel. The panel can then be managed with wxAUI.

Right now, only a mini frame is supported on wxAUI. I imagine that, in the future, we will support a style for a full dialog frame.